A novel mutation in the B3-adrenergic receptor gene was recently detected in a number of populations. This mutation predicts a minor amino acid change in the first intracellular loop of this seven membrane-spanning receptor. The B3 adrenergic receptor is thought to play an important role in the regulation of energy expenditure & lipolysis . Subjects who harbor the mutation tend to have a lower resting metabolic rate, higher body mass index & earlier onset of typeII diabetes.